Step 5: The charger/battery box (2):

Step 6: Put the box in your backpack and you're done!

Some more ideas/hints/tips: - The solar panels aren't critical, just make sure V Vdiode + 1.2V*number of batteries and Ishort circuit- A fuse on the...

In this instructable I'll show you how to build a detachable solar panel and battery charger for your backpack. This can power or charge all your gadgets (cell phone, mp3 player...) while on the road. HAMs can use it to power small QRP transmitters and receivers on a field day etc.
I was inspired by the excellent instructable "Rain or shine solar charger" by Blondietheblond, but wanted to avoid sewing, since I don't have a machine. So this is the result.

I want to do this on my school backpack, so it must be durable. I am looking at the flexible solar panels from Silicon Solar. It looks like it would take more panels to reach your requirement of 800 mA. Is 800 necessary? Is there a better option for durable solar cells that are fairly accident proof for everyday use?

Ok I finally got the bank to build one of these, now i have a few noob questions for you here,1. does this setup have a plugin for charging like via usb or anything? and if not could i add plugins and how easy would that be?2. what would i have to to to make something like this that could charge a laptop?

basically i want to make something like this where i can carry my laptop, phone, mp3 player, and my psp and charge them. idk if its possible....HELP!!

Most likely you would not be able to charge a laptop because of the amount of power a laptop takes (over 50 watts). If you wanted USB plugs, you would just buy a 5v voltage regulator from somewhere like radioshack and a usb jack and wire it up to the battery. Most things like cell phones and mp3's can be charged by this, but it takes time.

Hello, I'm building solar charger circuit for GPS assisted trek in Spanish Pyrenees. Made a "Mintyboost" circuit to keep pack of 3 1.2V AA's at 5V even when "drained" (To charge PDA and GPS receiver). Mintyboost IC steps up as low as 0.7V to 5V, so your circuit will be good addition if indeed deep discharging (0.7V) is not good for battery lifetime (although GP datasheet only mentions "prolonged charging time" after deep discharge). If I understand your circuit, the lower transistor "opens" the NDS332P, which has a higher current capacity (?). But how much current would there be "lost" through the lower transistor? (after all, after Spain, i'll be back in cloudy Belgium... :)

Here's a few questions How are the ND5332Ps hooked up? Does the gound refer to the ground of the battery, or the ground of the solar panels? And I'm a bit confused about how the panels are hooked up. And help would be much appreciated, as I'm designing a PCB for this.

Hi Lucidn, the NDS332P (Fairchild Semiconductor) are in parallel, meaning gate to gate, source to source and drain to drain. You can always do this with mosfets to increase the current capability (note: don't do this with bipolar transistors, as they have a negative resistance temperature coefficient). The solar panels are in series so you end up with two wires, positive (red) and a negative (black) . The black wire is the ground for the system,so for batteries, the circuit and the solar panels. If you are going through the trouble of designing a pcb for this, it might be a good idea to include a variable resistor in series with the 1Mohm.

Well after looking for a CAD program that's both free and for mac, I remembered I still had Appleworks, from before I upgraded to OSX. So I've been using that, designing the PCB and then shrinking it down to the right size.

Yenka is a good program and its free if you just want it for personal use. It's really an educational tool, but the electronics features allow you to design, test and create PCBs ready for manufacture for circuits. You can get it at www.yenka.com It has other things such as chemistry and physics and such, but the electronics stuff is what you might be interested in.

I don't think it is patentable; there is no inventiveness in it.Most patents are just a waste of money anyway.This text http://www.tinaja.com/glib/casagpat.pdfopended my eyes about patents.highly recommended reading.

What is the transistor you are using to the left of the 1Mohm resistor? I cant read your handwriting. I am returning to the semi-conductor scene after being out of the game since college 6 years ago. Is there anyway you can explain the parts needed exactly for this so i could build it. I need to get back into this and I think this project is the one for me. Sorry i know its asking alot because i know you have alot on your plate but it would be very much appreciated. Thank you sooooo much Dan M.

the one that is labeled 4748? Its circled in red in the picture. I just cant read the writing above it. I just want to use the same exact parts as you so i know it will work. Also where is a good place to buy all this stuff? I found the solar panels for cheap but all these other components are going to be hard to find local because in New York they dont have these kinds of stores anymore. Only circuit city's and they suck.

sorry for the handwriting... Thats a 1N4148 diode, also quite common. There's a gazillion other types of diodes that should do the same. Funny, you're from THE New York and there's no electronics shop nearby. I live in some backward little town in some Euro country, that's probably smaller than most of you're landfills, and at least we have one shop where I can get parts.What is this world coming to... :-)

yeh this city has severely gone the way of the "Big Business". None of the big stores carry components anymore. Its purely a "if it doesnt work right just swap it out for a new board" mentality. So sad. Great instructable by the way. I have been checking out the site for so long and nothing except the bread making has been in my price range or great interest. This hit me right where i like it though so ill let you know how it goes.

I am going to attempt to make this setup on my daypack/bike pack for charging my MP3 player, and integrate another Instructable for on-board lighting for night hiking or bicycling. I found the cells for 8 dollars American each. Good show mate. I like the project. -Brett